RFR: 8344330: Remove AccessController.doPrivileged() from jdk.charsets module

[Naoto Sato]

Removing a `AccessController.doPrivileged()` call from jdk.charsets module after JEP486 integration.

-------------

Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/22162/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22162&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344330
  Stats: 12 lines in 1 file changed: 0 ins; 9 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/22162.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22162/head:pull/22162

PR: https://git.openjdk.org/jdk/pull/22162